Movable heat exchanger

ABSTRACT

A heating, ventilating, and air conditioning (HVAC) system includes a heat exchanger configured to translate between a first position within an air flow path of the HVAC system and a second position external to the air flow path of the HVAC system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from and the benefit of U.S.Provisional Application Ser. No. 62/517,739, entitled “CONFORMING GASHEAT EXCHANGER,” filed Jun. 9, 2017, which is hereby incorporated byreference in its entirety for all purposes.

BACKGROUND

The present disclosure relates generally to heating, ventilating, andair conditioning (HVAC) systems, and specifically, to a heat exchangersystem for HVAC systems.

This section is intended to introduce the reader to various aspects ofart that may be related to various aspects of the present disclosure,which are described below. This discussion is believed to be helpful inproviding the reader with background information to facilitate a betterunderstanding of the various aspects of the present disclosure.Accordingly, it should be understood that these statements are to beread in this light, and not as admissions of prior art.

Environmental control systems are utilized in residential, commercial,and industrial environments to control environmental properties, such astemperature and humidity, for occupants of the respective environments.The environmental control system may control the environmentalproperties through control of an air flow delivered to and ventilatedfrom the environment. For example, a heating, ventilating, and airconditioning (HVAC) system may use heat exchangers to change thetemperature of air flowing through the HVAC system. The HVAC system maybe used to increase the temperature of the air flow to heat a home,office, hospital, or any other building. As such, the HVAC system mayuse a heat exchanger that heats the air flow during a heating mode ofthe HVAC system. In some cases, during a cooling mode of the HVACsystem, the air must still flow through the heat exchanger, regardlessof whether the heat exchanger is in operation during the cooling mode.

SUMMARY

A summary of certain embodiments disclosed herein is set forth below. Itshould be understood that these aspects are presented merely to providethe reader with a brief summary of these certain embodiments and thatthese aspects are not intended to limit the scope of this disclosure.Indeed, this disclosure may encompass a variety of aspects that may notbe set forth below.

In one embodiment, a heating, ventilating, and air conditioning (HVAC)system includes a heat exchanger configured to translate between a firstposition within an air flow path of the HVAC system and a secondposition external to the air flow path of the HVAC system.

In one embodiment, a method of operating a heating, ventilating, and airconditioning (HVAC) system includes operating the HVAC system in a firstmode with a heat exchanger disposed within an air flow path andoperating the HVAC system in a second mode with the heat exchangerpositioned external to the air flow path.

In one embodiment, a packaged heating, ventilating, and air conditioning(HVAC) unit, includes a heat source disposed within a first volume of ahousing of the packaged HVAC unit, and a heat exchanger disposed withina second volume of the housing of the packaged HVAC unit. The heatexchanger is configured to establish a heat exchange relationship withan air flow within the housing in a heating mode of the packaged HVACunit and the heat exchanger is configured to translate from within thesecond volume to a position external to the second volume in a coolingmode of the packaged HVAC unit.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects of this disclosure may be better understood upon readingthe following detailed description and upon reference to the drawings inwhich:

FIG. 1 is a schematic of an environmental control for buildingenvironmental management that may employ one or more HVAC units, inaccordance with an aspect of the present disclosure;

FIG. 2 is a perspective view of an embodiment of a HVAC unit that may beused in the environmental control system of FIG. 1, in accordance withan aspect of the present disclosure;

FIG. 3 is a schematic of a residential heating and cooling system, inaccordance with an aspect of the present disclosure;

FIG. 4 is a schematic of an embodiment of a vapor compression systemthat can be used in any of the systems of FIGS. 1-3, in accordance withan aspect of the present disclosure;

FIG. 5 is a perspective view of an embodiment of a HVAC unit, inaccordance with an aspect of the present disclosure;

FIG. 6 is a perspective view of the embodiment of the HVAC unit of FIG.5 in an additional configuration, in accordance with an aspect of thepresent disclosure;

FIG. 7 is a perspective view of an embodiment of a HVAC unit, inaccordance with an aspect of the present disclosure;

FIG. 8 is a perspective view of the embodiment of the HVAC unit of FIG.7 in an additional configuration, in accordance with an aspect of thepresent disclosure;

FIG. 9 is a perspective view of an embodiment of a HVAC unit, inaccordance with an aspect of the present disclosure;

FIG. 10 is a perspective view of the embodiment of the HVAC unit of FIG.9 in an additional configuration, in accordance with an aspect of thepresent disclosure;

FIG. 11 is a perspective view of an embodiment of a HVAC unit using aprotection system, in accordance with an aspect of the presentdisclosure;

FIG. 12 is a perspective view of the embodiment of the HVAC unit of FIG.11 in an additional configuration, in accordance with an aspect of thepresent disclosure;

FIG. 13 is a perspective view of an embodiment of a HVAC unit using aprotection system, in accordance with an aspect of the presentdisclosure;

FIG. 14 is a perspective view of the embodiment of the HVAC unit of FIG.13 in an additional configuration, in accordance with an aspect of thepresent disclosure;

FIG. 15 is a perspective view of an embodiment of a HVAC unit using aprotection system, in accordance with an aspect of the presentdisclosure;

FIG. 16 is a perspective view of the embodiment of the HVAC unit of FIG.15 in an additional configuration, in accordance with an aspect of thepresent disclosure; and

FIG. 17 is a block diagram of an embodiment of a process to changeoperating modes of a HVAC unit that can be used in any of the systems inFIGS. 5-16, in accordance with an aspect of the present disclosure.

DETAILED DESCRIPTION

One or more specific embodiments will be described below. In an effortto provide a concise description of these embodiments, not all featuresof an actual implementation are described in the specification. Itshould be appreciated that in the development of any such actualimplementation, as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would nevertheless be aroutine undertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

The present disclosure is directed to heating, ventilating, and airconditioning (HVAC) systems that use a heat exchanger for increasing thetemperature in air flowing through the HVAC system. In some embodiments,the heat exchanger may be disposed in a packaged unit capable of bothheating and cooling an air flow, such as a supply air flow. As anexample, the heat exchanger may be located along an air flow path of theHVAC system and thus, the air flow may flow through or across the heatexchanger. The heat exchanger may transfer heat to the air flow toincrease the temperature of the air flow before it is supplied to aconditioned space. The air flow may then be circulated, such as viaductwork, to heat different areas of a building conditioned by the HVACsystem. To circulate the air flow, the HVAC system may use a blower thatincreases the velocity of the air flow. The heat exchanger may create aresistance in the air flow path that decreases the velocity of the airflow, and thus the blower may be located upstream of the heat exchangerto compensate and increase the velocity of the air flow prior to flowingacross the heat exchanger. As a result, the air flow may flow across theheat exchanger and exit the HVAC system at a desired velocity.

Generally, the heat exchanger may operate during a heating mode in theHVAC system to increase the temperature of the air flow. For example,during the heating mode, the heat exchanger may contain a heated fluid,such as a combusted gas, that transfers heat to the air flow as the airflow passes across the heat exchanger. However, in some cases, such asduring a cooling mode in the HVAC system, the heat exchanger may not bein operation so as to not increase the temperature of the air flow. Forexample, the heat exchanger may not contain the heated fluid when theHVAC system operates in the cooling mode. Therefore, the temperature ofthe air flow may remain substantially the same before and after passingacross the heat exchanger. Since the heat exchanger may remain in theair flow path of the HVAC system during the cooling mode, the heatexchanger may still be a source of a resistance in the air flow.

In accordance with certain embodiments of the present disclosure, it isnow recognized that removing the heat exchanger from the air flow pathwhen the heat exchanger is not operated to condition the air flow maydecrease the hydraulic resistance in the HVAC system. That is, it ispresently recognized that removing the heat exchanger from the air flowpath when not in use may reduce an undesired decrease in velocity of theair flow and/or reduce a pressure drop in the air flow. As such, theblower may operate at a lower level, thereby enabling energy oroperational cost savings.

Removing the heat exchanger from the air flow path may be accomplishedin various ways, as described below. As an example, the blower and theheat exchanger may be disposed in a section within the HVAC system orunit. Within the section, the heat exchanger may be located in an areabetween the blower and an opening leading to the ductwork or buildingconditioned by the HVAC system, such that air exiting the blower isdirected across the heat exchanger and toward the opening. When the HVACsystem switches from the heating mode to the cooling mode, the heatexchanger may be moved, such that air exiting the blower flows directlyinto the opening. In other words, when the heat exchanger is moved, theheat exchanger is not in the air flow path between the blower and theopening of the building or ductwork. Conversely, when the HVAC systemswitches from the cooling mode to the heating mode, the heat exchangermay return to its original position within the section so that air mayflow across the heat exchanger to increase in temperature in the heatingmode before the air is supplied to the building or ductwork.

The heat exchanger system may be used in association with any number ofHVAC systems, including those in residential and commercial settings.For example, the heat exchanger system may be utilized in a rooftop unit(RTU), a dedicated outdoor air system, or a split system. Non-limitingexamples of systems that may use the heat exchanger system of thepresent disclosure are described herein with respect to FIGS. 1-4.

Turning now to the drawings, FIG. 1 illustrates a heating, ventilating,and air conditioning (HVAC) system for building environmental managementthat may employ one or more HVAC units. In the illustrated embodiment, abuilding 10 is air conditioned by a system that includes an HVAC unit12. The building 10 may be a commercial structure or a residentialstructure. As shown, the HVAC unit 12 is disposed on the roof of thebuilding 10; however, the HVAC unit 12 may be located in other equipmentrooms or areas adjacent the building 10. The HVAC unit 12 may be asingle packaged unit containing other equipment, such as a blower,integrated air handler, and/or auxiliary heating unit. In otherembodiments, the HVAC unit 12 may be part of a split HVAC system, suchas the system shown in FIG. 3, which includes an outdoor HVAC unit 58and an indoor HVAC unit 56.

The HVAC unit 12 is an air cooled device that implements a refrigerationcycle to provide conditioned air to the building 10. Specifically, theHVAC unit 12 may include one or more heat exchangers across which an airflow is passed to condition the air flow before the air flow is suppliedto the building. In the illustrated embodiment, the HVAC unit 12 is arooftop unit (RTU) that conditions a supply air stream, such asenvironmental air and/or a return air flow from the building 10. Afterthe HVAC unit 12 conditions the air, the air is supplied to the building10 via ductwork 14 extending throughout the building 10 from the HVACunit 12. For example, the ductwork 14 may extend to various individualfloors or other sections of the building 10. In certain embodiments, theHVAC unit 12 may be a heat pump that provides both heating and coolingto the building with one refrigeration circuit configured to operate indifferent modes. In other embodiments, the HVAC unit 12 may include oneor more refrigeration circuits for cooling an air stream and a furnacefor heating the air stream.

A control device 16, one type of which may be a thermostat, may be usedto designate the temperature of the conditioned air. The control device16 also may be used to control the flow of air through the ductwork 14.For example, the control device 16 may be used to regulate operation ofone or more components of the HVAC unit 12 or other components, such asdampers and fans, within the building 10 that may control flow of airthrough and/or from the ductwork 14. In some embodiments, other devicesmay be included in the system, such as pressure and/or temperaturetransducers or switches that sense the temperatures and pressures of thesupply air, return air, and so forth. Moreover, the control device 16may include computer systems that are integrated with or separate fromother building control or monitoring systems, and even systems that areremote from the building 10.

FIG. 2 is a perspective view of an embodiment of the HVAC unit 12. Inthe illustrated embodiment, the HVAC unit 12 is a single package unitthat may include one or more independent refrigeration circuits andcomponents that are tested, charged, wired, piped, and ready forinstallation. The HVAC unit 12 may provide a variety of heating and/orcooling functions, such as cooling only, heating only, cooling withelectric heat, cooling with dehumidification, cooling with gas heat, orcooling with a heat pump. As described above, the HVAC unit 12 maydirectly cool and/or heat an air stream provided to the building 10 tocondition a space in the building 10.

As shown in the illustrated embodiment of FIG. 2, a cabinet 24 enclosesthe HVAC unit 12 and provides structural support and protection to theinternal components from environmental and other contaminants. In someembodiments, the cabinet 24 may be constructed of galvanized steel andinsulated with aluminum foil faced insulation. Rails 26 may be joined tothe bottom perimeter of the cabinet 24 and provide a foundation for theHVAC unit 12. In certain embodiments, the rails 26 may provide accessfor a forklift and/or overhead rigging to facilitate installation and/orremoval of the HVAC unit 12. In some embodiments, the rails 26 may fitinto “curbs” on the roof to enable the HVAC unit 12 to provide air tothe ductwork 14 from the bottom of the HVAC unit 12 while blockingelements such as rain from leaking into the building 10.

The HVAC unit 12 includes heat exchangers 28 and 30 in fluidcommunication with one or more refrigeration circuits. Tubes within theheat exchangers 28 and 30 may circulate refrigerant, such as R-410A,through the heat exchangers 28 and 30. The tubes may be of varioustypes, such as multichannel tubes, conventional copper or aluminumtubing, and so forth. Together, the heat exchangers 28 and 30 mayimplement a thermal cycle in which the refrigerant undergoes phasechanges and/or temperature changes as it flows through the heatexchangers 28 and 30 to produce heated and/or cooled air. For example,the heat exchanger 28 may function as a condenser where heat is releasedfrom the refrigerant to ambient air, and the heat exchanger 30 mayfunction as an evaporator where the refrigerant absorbs heat to cool anair stream. In other embodiments, the HVAC unit 12 may operate in a heatpump mode where the roles of the heat exchangers 28 and 30 may bereversed. That is, the heat exchanger 28 may function as an evaporatorand the heat exchanger 30 may function as a condenser. In furtherembodiments, the HVAC unit 12 may include a furnace for heating the airstream that is supplied to the building 10. While the illustratedembodiment of FIG. 2 shows the HVAC unit 12 having two of the heatexchangers 28 and 30, in other embodiments, the HVAC unit 12 may includeone heat exchanger or more than two heat exchangers.

The heat exchanger 30 is located within a compartment 31 that separatesthe heat exchanger 30 from the heat exchanger 28. Fans 32 draw air fromthe environment through the heat exchanger 28. Air may be heated and/orcooled as the air flows through the heat exchanger 28 before beingreleased back to the environment surrounding the rooftop unit 12. Ablower assembly 34, powered by a motor 36, draws air through the heatexchanger 30 to heat or cool the air. The heated or cooled air may bedirected to the building 10 by the ductwork 14, which may be connectedto the HVAC unit 12. Before flowing through the heat exchanger 30, theconditioned air flows through one or more filters 38 that may removeparticulates and contaminants from the air. In certain embodiments, thefilters 38 may be disposed on the air intake side of the heat exchanger30 to prevent contaminants from contacting the heat exchanger 30.

The HVAC unit 12 also may include other equipment for implementing thethermal cycle. Compressors 42 increase the pressure and temperature ofthe refrigerant before the refrigerant enters the heat exchanger 28. Thecompressors 42 may be any suitable type of compressors, such as scrollcompressors, rotary compressors, screw compressors, or reciprocatingcompressors. In some embodiments, the compressors 42 may include a pairof hermetic direct drive compressors arranged in a dual stageconfiguration 44. However, in other embodiments, any number of thecompressors 42 may be provided to achieve various stages of heatingand/or cooling. As may be appreciated, additional equipment and devicesmay be included in the HVAC unit 12, such as a solid-core filter drier,a drain pan, a disconnect switch, an economizer, pressure switches,phase monitors, and humidity sensors, among other things.

The HVAC unit 12 may receive power through a terminal block 46. Forexample, a high voltage power source may be connected to the terminalblock 46 to power the equipment. The operation of the HVAC unit 12 maybe governed or regulated by a control board 48. The control board 48 mayinclude control circuitry connected to a thermostat, sensors, andalarms. One or more of these components may be referred to hereinseparately or collectively as the control device 16. The controlcircuitry may be configured to control operation of the equipment,provide alarms, and monitor safety switches. Wiring 49 may connect thecontrol board 48 and the terminal block 46 to the equipment of the HVACunit 12.

FIG. 3 illustrates a residential heating and cooling system 50, also inaccordance with present techniques. The residential heating and coolingsystem 50 may provide heated and cooled air to a residential structure,as well as provide outside air for ventilation and provide improvedindoor air quality (IAQ) through devices such as ultraviolet lights andair filters. In the illustrated embodiment, the residential heating andcooling system 50 is a split HVAC system. In general, a residence 52conditioned by a split HVAC system may include refrigerant conduits 54that operatively couple the indoor unit 56 to the outdoor unit 58. Theindoor unit 56 may be positioned in a utility room, an attic, abasement, and so forth. The outdoor unit 58 is typically situatedadjacent to a side of residence 52 and is covered by a shroud to protectthe system components and to prevent leaves and other debris orcontaminants from entering the unit. The refrigerant conduits 54transfer refrigerant between the indoor unit 56 and the outdoor unit 58,typically transferring primarily liquid refrigerant in one direction andprimarily vaporized refrigerant in an opposite direction.

When the system shown in FIG. 3 is operating as an air conditioner, aheat exchanger 60 in the outdoor unit 58 serves as a condenser forre-condensing vaporized refrigerant flowing from the indoor unit 56 tothe outdoor unit 58 via one of the refrigerant conduits 54. In theseapplications, a heat exchanger 62 of the indoor unit functions as anevaporator. Specifically, the heat exchanger 62 receives liquidrefrigerant, which may be expanded by an expansion device, andevaporates the refrigerant before returning it to the outdoor unit 58.

The outdoor unit 58 draws environmental air through the heat exchanger60 using a fan 64 and expels the air above the outdoor unit 58. Whenoperating as an air conditioner, the air is heated by the heat exchanger60 within the outdoor unit 58 and exits the unit at a temperature higherthan it entered. The indoor unit 56 includes a blower or fan 66 thatdirects air through or across the indoor heat exchanger 62, where theair is cooled when the system is operating in air conditioning mode.Thereafter, the air is passed through ductwork 68 that directs the airto the residence 52. The overall system operates to maintain a desiredtemperature as set by a system controller. When the temperature sensedinside the residence 52 is higher than the set point on the thermostat,or the set point plus a small amount, the residential heating andcooling system 50 may become operative to refrigerate additional air forcirculation through the residence 52. When the temperature reaches theset point, or the set point minus a small amount, the residentialheating and cooling system 50 may stop the refrigeration cycletemporarily.

The residential heating and cooling system 50 may also operate as a heatpump. When operating as a heat pump, the roles of heat exchangers 60 and62 are reversed. That is, the heat exchanger 60 of the outdoor unit 58will serve as an evaporator to evaporate refrigerant and thereby coolair entering the outdoor unit 58 as the air passes over the outdoor heatexchanger 60. The indoor heat exchanger 62 will receive a stream of airblown over it and will heat the air by condensing the refrigerant.

In some embodiments, the indoor unit 56 may include a furnace system 70.For example, the indoor unit 56 may include the furnace system 70 whenthe residential heating and cooling system 50 is not configured tooperate as a heat pump. The furnace system 70 may include a burnerassembly and heat exchanger, among other components, inside the indoorunit 56. Fuel is provided to the burner assembly of the furnace 70 whereit is mixed with air and combusted to form combustion products. Thecombustion products may pass through tubes or piping in a heatexchanger, separate from heat exchanger 62, such that air directed bythe blower 66 passes over the tubes or pipes and extracts heat from thecombustion products. The heated air may then be routed from the furnacesystem 70 to the ductwork 68 for heating the residence 52.

FIG. 4 is an embodiment of a vapor compression system 72 that can beused in any of the systems described above. The vapor compression system72 may circulate a refrigerant through a circuit starting with acompressor 74. The circuit may also include a condenser 76, an expansionvalve(s) or device(s) 78, and an evaporator 80. The vapor compressionsystem 72 may further include a control panel 82 that has an analog todigital (A/D) converter 84, a microprocessor 86, a non-volatile memory88, and/or an interface board 90. The control panel 82 and itscomponents may function to regulate operation of the vapor compressionsystem 72 based on feedback from an operator, from sensors of the vaporcompression system 72 that detect operating conditions, and so forth.

In some embodiments, the vapor compression system 72 may use one or moreof a variable speed drive (VSDs) 92, a motor 94, the compressor 74, thecondenser 76, the expansion valve or device 78, and/or the evaporator80. The motor 94 may drive the compressor 74 and may be powered by thevariable speed drive (VSD) 92. The VSD 92 receives alternating current(AC) power having a particular fixed line voltage and fixed linefrequency from an AC power source, and provides power having a variablevoltage and frequency to the motor 94. In other embodiments, the motor94 may be powered directly from an AC or direct current (DC) powersource. The motor 94 may include any type of electric motor that can bepowered by a VSD or directly from an AC or DC power source, such as aswitched reluctance motor, an induction motor, an electronicallycommutated permanent magnet motor, or another suitable motor.

The compressor 74 compresses a refrigerant vapor and delivers the vaporto the condenser 76 through a discharge passage. In some embodiments,the compressor 74 may be a centrifugal compressor. The refrigerant vapordelivered by the compressor 74 to the condenser 76 may transfer heat toa fluid passing across the condenser 76, such as ambient orenvironmental air 96. The refrigerant vapor may condense to arefrigerant liquid in the condenser 76 as a result of thermal heattransfer with the environmental air 96. The liquid refrigerant from thecondenser 76 may flow through the expansion device 78 to the evaporator80.

The liquid refrigerant delivered to the evaporator 80 may absorb heatfrom another air stream, such as a supply air stream 98 provided to thebuilding 10 or the residence 52. For example, the supply air stream 98may include ambient or environmental air, return air from a building, ora combination of the two. The liquid refrigerant in the evaporator 80may undergo a phase change from the liquid refrigerant to a refrigerantvapor. In this manner, the evaporator 38 may reduce the temperature ofthe supply air stream 98 via thermal heat transfer with the refrigerant.Thereafter, the vapor refrigerant exits the evaporator 80 and returns tothe compressor 74 by a suction line to complete the cycle.

In some embodiments, the vapor compression system 72 may further includea reheat coil in addition to the evaporator 80. For example, the reheatcoil may be positioned downstream of the evaporator relative to thesupply air stream 98 and may reheat the supply air stream 98 when thesupply air stream 98 is overcooled to remove humidity from the supplyair stream 98 before the supply air stream 98 is directed to thebuilding 10 or the residence 52.

It should be appreciated that any of the features described herein maybe incorporated with the HVAC unit 12, the residential heating andcooling system 50, or other HVAC systems. Additionally, while thefeatures disclosed herein are described in the context of embodimentsthat directly heat and cool a supply air stream provided to a buildingor other load, embodiments of the present disclosure may be applicableto other HVAC systems as well. For example, the features describedherein may be applied to mechanical cooling systems, free coolingsystems, chiller systems, or other heat pump or refrigerationapplications.

As noted above, air may flow through a HVAC system, where itstemperature may be increased by a heat exchanger, such as via thefurnace system 70 of FIG. 3, in a heating mode. As such, the heatexchanger may be disposed within an air flow path that the air flowsthrough. Further, the heat exchanger may be coupled to a heat source,such as a burner that generates combustion products, to provide heat toair flowing through or across the heat exchanger. In accordance withpresent embodiments, the heat exchanger may be a part of a heatexchanger system within the HVAC system, where the heat exchanger systemmay remove the heat exchanger from the air flow path when the heatexchanger is not in operation. For example, the heat exchanger systemmay move the heat exchanger out of the air flow path when the HVACsystem is in a cooling mode. During cooling mode, the heat exchanger maynot be used for heating the air flow and thus, may not be in operation.In some embodiments, the heat exchanger system may include a mechanismto remove the heat exchanger from the air flow path while protecting theheat exchanger after the heat exchanger has been removed. The heatexchanger system may also re-position the heat exchanger within the airflow path during heating mode of the HVAC system when the heat exchangeris used for heating the air flow. Thus, the HVAC system changes theposition of the heat exchanger to correspond with the mode of operationof the HVAC system. For purposes of discussion, the disclosure willrefer to the heat exchanger as it may be utilized in a packaged unit,such as the HVAC unit 12 of FIGS. 1 and 2. However, the systems andconcepts described below may be used in other types of HVAC systems,such as the residential heating and cooling system 50 of FIG. 3.

FIG. 5 is a perspective view an embodiment of a packaged unit 100 thatmay use the heat exchanger system mentioned above. In the illustratedembodiment, the packaged unit 100 includes multiple components enclosedwithin an internal volume of a housing 102 of the packaged unit 100. Thepackaged unit 100 may be configured to circulate air and therefore mayinclude a return section 104 to take in air flow, such as a return airflow from building 10, and a supply section 106 to output air flow. Asan example, the packaged unit 100 may be located in an outsideenvironment, such as on a rooftop, and may be coupled to ductwork thatleads to rooms or other areas within a building, such as building 10 ofFIG. 1. The ductwork may couple to the return section 104 and the supplysection 106. In this manner, the packaged unit 100 may circulate air inthe building 10.

In addition to circulating air, the packaged unit 100 may change thetemperature of the air flow. For example, the packaged unit 100 mayinclude a refrigerant circuit that circulates a refrigeranttherethrough, where the refrigerant circuit is in thermal communicationwith the air flow. The refrigerant may flow through a condenser 108,where the refrigerant may be cooled. FIG. 5 illustrates the condenser108 as using a fan that may blow ambient air over the condenser 108 toremove heat from the refrigerant via convection, but in otherembodiments, the condenser 108 may use another means of cooling therefrigerant, such as via a coolant. After being cooled, the refrigerantmay then flow through an evaporator 110, where the refrigerant mayinteract with the air flow by receiving heat from the air flow. Thus,the refrigerant may be heated and the air flow may be cooled at theevaporator 110. After being heated at the evaporator 110, therefrigerant may return to the condenser 108 where it may once again becooled.

The packaged unit 100 may be capable of operating in a heating mode anda cooling mode. During operation of the heating mode, air may be takeninto the packaged unit 100 at the return section 104 to enter an airflow path. As mentioned, air may be taken in from ductwork that isconnected to a building. However, in other embodiments, air may be takenin from ambient air, such as from an outside environment. In certainembodiments, the air flow passing through the packaged unit 100 mayinclude air from the return section 104 and from ambient. After the airflow enters the packaged unit 100, the air flow may pass through afilter 112. The filter 112 may remove particles from the air flow, suchas dirt and other debris. The filter 112 may be a pleated filter, anelectrostatic filter, a HEPA filter, or a fiber glass filter that trapsthe debris when the air flow passes through the filter 112. After beingfiltered, the air flow may be directed to the evaporator 110. Asdiscussed above, at the evaporator 110, the air flow may be cooled bytransferring heat to the refrigerant within the evaporator 110. Inaddition, cooling the air flow may also remove moisture from the airflow and thus, the packaged unit 100 may also dehumidify the air flow.Once cooled, the air flow may be directed to a blower 114, which mayincrease the velocity of the air flow to exit the supply section 106 ofthe packaged unit 100 at a high enough velocity, such as to becirculated through the ductwork. In some embodiments, the blower 114 mayalso operate to draw air in through the return section 104 and therebyfunction to both draw in and expel air.

In some modes of operation, prior to exiting the packaged unit 100, theair may be heated by a heat exchanger 116. By way of example, the heatexchanger 116 may be coupled to a heat source, which is not shown inFIG. 5. The heat source may be coupled to the heat exchanger 116 atattachment coil segments 118. In some embodiments, the heat exchanger116 may be a gas heat exchanger and may be coupled with a gas burnerthat combusts a gas, such as acetylene, natural gas, propane, anothergas, or any combination thereof to flow into the heat exchanger 116 atan elevated temperature. When the air flow is directed across the heatexchanger 116, the air flow may absorb heat from the combusted gas,thereby increasing the temperature of the air flow. In some embodiments,there may be an additional heat exchanger that further heats the airflow to increase the heating efficiency of the packaged unit 100.Thereafter, the air flow may then exit the packaged unit 100 at a highertemperature compared to when the air flow entered the packaged unit 100.

To separate the components within the packaged unit 100, the packagedunit 100 may include partitions 120. As an example, the partitions 120may divide the internal volume within the housing 102 into a firstvolume 122 that contains the heat source, a second volume 124 where theair flow may exit the packaged unit 100, a third volume 126 thatcontains the condenser 108, and a fourth volume 128 where air flow mayenter the packaged unit 100.

As mentioned above, the packaged unit 100 may operate in a cooling mode.During the cooling mode, the heat exchanger 116 may not be operating toheat the air flow because the increase of temperature would not bedesirable. Therefore, in present embodiments, the heat exchanger 116 maybe moved so that the air flow, after being cooled in the evaporator 110,may be directed straight from the blower 114 to the supply section 106to exit the packaged unit 100. That is, the heat exchanger 116 may bemoved out of the second volume 124 such that the heat exchanger 116 isno longer in the air flow path between the blower 114 and the supplysection 106. If the packaged unit 100 includes the additional heatexchanger, the additional heat exchanger may also be moved out of thesecond volume 124. In some embodiments, the additional heat exchangermay be moved out of the second volume 124 simultaneously when the heatexchanger 116 is moved out of the second volume 124. In thisconfiguration, the air flow may directly exit the packaged unit 100 fromthe blower 114. As such, the blower 114 may operate at a lower powerbecause the blower 114 may no longer compensate for velocity lossresulting from the resistance caused by the heat exchanger 116. Forexample, the blower 114 may include a fan coupled to a VSD fan motor.The VSD fan motor may rotate the fan at a lower speed in the coolingmode than in the heating mode and thus save energy costs to operate theVSD fan motor.

FIG. 6 is a perspective view of an embodiment of the packaged unit 100operating in the cooling mode. As shown in FIG. 6, the heat exchanger116 is part of a heat exchanger system 150 that may move or translateout of the second volume 124. The heat exchanger system 150 may includea translation mechanism 152 that enables the heat exchanger system 150to be removed from the second volume 124, such as via sliding, rotating,another suitable movement, or any combination thereof. In someembodiments, the heat exchanger system 150 may move out of the secondvolume 124 in a direction 154, as illustrated in FIG. 6. For example,the translation mechanism 152 may include rails 156 to guide the heatexchanger system 150 in the direction 154. When the heat exchangersystem 150 is moved out of the second volume 124, the air flow maybypass flowing across the heat exchanger 116 when exiting through thesupply section 106. Furthermore, since moving the heat exchanger system150 out of the second volume 124 may substantially remove the heatexchangers system 150 from the housing 102 of the packaged unit 100, theheat exchanger system 150 may include a protection system that coversthe heat exchanger system 150 to block external elements, such as leavesor precipitation, from contacting the heat exchanger system 150. Theposition of the heat exchanger system 150 during the cooling mode may beconsidered an extended position, because the heat exchanger system 150is extended out of the housing 102. Likewise, the position of the heatexchanger system 150 during the heating mode may be considered aretracted position, because heat exchanger system 150 is retractedwithin the housing 102.

To move the heat exchanger system 150 between the extended positionshown in FIG. 6 and the retracted position shown in FIG. 5, the packagedunit 100 may include a controller 156 configured to adjust the positionof the heat exchanger system 150 based on the operating mode of thepackaged unit 100. For example, the controller 156 may receive a signalindicating a desired operation of the cooling mode, and, in response,the controller 156 may operate to move the heat exchanger system 150 tothe extended position shown in FIG. 6. At a different time, thecontroller 156 may receive a signal indicating a desired operation ofthe heating mode, and, in response, the controller 156 may operate tomove the heat exchanger system 150 back into the second volume 124 inthe retracted position, such as that shown in FIG. 5. To facilitatemovement of the heat exchanger system 150, the controller 156 mayinclude a memory with stored instructions for controlling the heatexchanger system 150, and a processor configured to execute suchinstructions. For example, the processor may include one or moreapplication specific integrated circuits (ASICs), one or more fieldprogrammable gate arrays (FPGAs), one or more general purposeprocessors, or any combination thereof. Additionally, the memory mayinclude volatile memory, such as random access memory (RAM), and/ornon-volatile memory, such as read-only memory (ROM), optical drives,hard disc drives, or solid-state drives. Although FIG. 6 illustrates thecontroller 156 as being disposed within the packaged unit 100, in someembodiments, the controller 156 may be external to the packaged unit100, such as attached to the outside of the housing 102, or thecontroller 156 may be located remotely relative to the packaged unit100.

When the heat exchanger system 150 is in the extended position, theattachment coil segments 118 of the heat exchanger 116 may decouple fromthe heat source such that the heat source remains inside the packagedunit 100. As such, the heat source may be exposed to the second volume124. To protect the heat source from the air flow, and vice versa, whenthe heat exchanger system 150 is in the extended position, the packagedunit 100 may include a plate system 158. The plate system 158 may be apart of the partitions 120 disposed in the packaged unit 100. When theheat exchanger system 150 is in the extended position, the plate system158 may translate to cover the heat source, thereby blocking the airflow from traveling from the second volume 124 to the first volume 122.

FIGS. 7-10 illustrate embodiments of the plate system 158 to block airflow from the second volume 124 to the first volume 122 when the heatexchanger system 150 is in the extended position. FIG. 7 is aperspective view of a packaged unit 200 that includes a horizontal platesystem 202. The horizontal plate system 202 may be disposed adjacent toa heat exchanger system 150 such that the horizontal plate system 202moves with the heat exchanger system 150. That is, the horizontal platesystem 202 may move along the direction 206 as the heat exchanger system150 moves in and out of the packaged unit 200. The horizontal platesystem 202 may include a first plate 208 that couples to the heatexchanger system 150. The first plate 208 may be located in a firstvolume 212 of the packaged unit 200 when the heat exchanger system 204is in the retracted position within a second volume 214 of the packagedunit 200. The first plate 208 may be positioned in a manner as to notinterfere with a connection between a heat source 216 and a heatexchanger of the heat exchanger system 150. In addition, the horizontalplate system 202 includes a second plate 218 coupled to the first plate208 and is disposed in a third volume 220 of the packaged unit 200 whenthe heat exchanger system 150 is within the second volume 214. When theheat exchanger system 150 is in the retracted position, the second plate218 may be in a first position, where the second plate 218 overlaps withthe partition 222 that separates the third volume 220 from a fourthvolume 224. When the heat exchanger system 150 is in the extendedposition, the second plate 218 may be in a second position, where thesecond plate 218 is located between the first volume 212 and the secondvolume 214 to block air flow from entering the first volume 212 from thesecond volume 214.

For example, FIG. 8 illustrates the packaged unit 200 when the heatexchanger system 150 is in the extended position. As discussed above, inthe extended position, the heat source 216 may decouple from the heatexchanger 116, thereby exposing the heat source 216 and the first volume212 to the second volume 214. As the heat exchanger system 150 extends,the second plate 218 translates to the second position to separate thefirst volume 212 from the second volume 214. In one embodiment, as aresult of translating the heat exchanger system 150 out of the secondvolume 214 of the packaged unit 200, the second plate 218 slides in adirection 230. In this manner, the second plate 218 moves from the thirdvolume 220 to the first volume 212. As an example, the first plate 208may be coupled to the heat exchanger system 150, and the second plate218 may be coupled to the first plate 208. In this manner, when the heatexchanger system 150 translates out of the second volume 214, the heatexchanger system 150 draws the first plate 208 out of the second volume214 which further draws the second plate 218 to the second positiondiscussed above. Coupling between the first plate 208 and the heatexchanger system 150 and/or the coupling between the first plate 208 andthe second plate 218 may be via springs, a pulley system, a linkagemechanism, fasteners, welds, brazes, another suitable method, or anycombination thereof. In one embodiment, the first and second plates 208and 218 may be a single piece structure. In the extended position of theheat exchanger system 150, the partition 222 may continue to separatethe third volume 220 from the fourth volume 224. The horizontal platesystem 202 may be arranged in such a manner that the first plate 208and/or the second plate 218 overlaps with a partition 232 disposed inbetween the first volume 212 and the second volume 214. For example, thefirst plate 208 and/or the second plate 218 may translate along rails234 that guide the movement of the first plate 208 and/or the secondplate 218. The partition 232 may separate the first volume 212 and thesecond volume 214, and the partition 232 may contain a gap or otherapertures to enable the heat source 216 to couple with the heatexchanger 116 of the heat exchanger system 150. In the retractedposition, the first plate 208 and the coupling between the heat sources216 and the heat exchanger 116 of the heat exchanger system 150 mayblock air flow from the second volume 214 to the first volume 212. Inthe extended position, the second plate 218 may cover the gap orapertures in the partition 232 to block air from flowing from the secondvolume 214 to the first volume 212.

Another embodiment of a system to separate the first volume 212 from thesecond volume 214 when the heat exchanger system 150 is in the extendedposition is illustrated in FIG. 9. Specifically, FIG. 9 is a perspectiveview of an embodiment of a packaged unit 250 that includes a verticalplate system 252. The vertical plate system 252 may be disposed in afirst volume 254 that also contains a heat source 256. The verticalplate system 252 includes a plate 258 configured to move in a direction260. For example, when the heat exchanger system 150 is in the retractedposition, the plate 258 may be in a first position above the heat source256. When the heat exchanger system 150 translates to the extendedposition, which may expose the heat source 256 to the second volume 264,the plate 258 moves downward to a second position to block air flow fromthe first volume 254 to the second volume 264 and vice versa. When theheat exchanger system 150 is in the retracted position, the plate 258moves upwards back to the first position to enable the heat source 256to couple with the heat exchanger 116 of the heat exchanger system 150.The packaged unit 250 may use a vertical translation mechanism 266 toenable the plate 258 to move in the direction 260. For example, the heatexchanger system 150 may be coupled to an adapter plate 268 that maymove with the heat exchanger system 150 as the heat exchanger system 150translates between the extended and retracted positions. In theretracted position, the plate 258 and the adapter plate 268 may overlapwith a partition 270 that separates the first volume 254 from the secondvolume 264. As discussed above, the partition 270 may include a gap orother apertures to enable the heat source 256 to couple with a heatexchanger 116 of the heat exchanger system 150 disposed in the secondvolume 264. The gap or apertures may allow air flow into the firstvolume 254 when the heat source 256 decouples from the heat exchanger116 of the heat exchanger system 150. Thus, in the extended position,the plate 258 translates downward to obstruct or close the gap orapertures in the partition 270 to block air flow into the first volume254 from the second volume 264 and vice versa.

To illustrate the movement of the plate 258, FIG. 10 is a perspectiveview of the packaged unit 250 when the heat exchanger system 150 is inthe extended position. As shown in FIG. 10, the plate 258 has moved inthe direction 280 to the second position. As such, the plate 258 closesor blocks the gap or apertures between the first volume 254 and thesecond volume 264. For example, as the adapter plate 268 moves with theheat exchanger system 150 when the heat exchanger system 150 translatesto the extended position, the plate 258 may move in the direction 280.To this end, the plate 258 may be coupled to the adapter plate 268 viasprings, a pulley system, a linkage mechanism, actuators that may becontrolled by a position control synchronous motor and/or direct currentmotor, another suitable component, or any combination thereof to enablethe plate 258 to move in the direction 280 when the adapter plate 268moves. In some embodiments, the plate 258 may slide along rails 282 toguide the plate 258 to move in the direction 280 along the partition270.

In the packaged units 200 and 250, the respective heat sources 216, 256may remain within the respective first volumes 212, 254, even whendecoupled from the corresponding heat exchangers 116. As a result,couplings, such as fuel lines, between the respective heat sources 216,256 and other components may be via fixed gas connectors, metal piping,tubing of another material, another coupling component, or anycombination thereof.

As previously noted, in packaged units that include the systemsdiscussed above, translating the heat exchanger system outside of theinternal volume of the packaged unit may expose the heat exchangersystem to external elements. To protect the heat exchanger system whenit is in the extended position, the packaged unit and/or the heatexchanger system may include a protection system that shrouds the heatexchanger system. FIGS. 11-16 illustrates different embodiments of theprotection system that may be utilized for the heat exchanger system.

FIG. 11 illustrates an embodiment of a packaged unit 300 that uses aprotection system 302. The protection system 302 is configured toenclose a heat exchanger system that is moved in and out of a housing304 of the packaged unit 300. The protection system 302 may be coupledto an opening 306 disposed on a side of the packaged unit 300 throughwhich the heat exchanger system may translate. The protection system 302may also be coupled to the heat exchanger system such that theprotection system 302 adjusts its configuration based on the position ofthe heat exchanger. For example, FIG. 11 illustrates the protectionsystem 302 in an extended position, such as during a cooling mode of thepackaged unit 300 when the heat exchanger is also in the extendedposition. To enable the protection system 302 to adjust itsconfiguration, the protection system 302 in the illustrated embodimentinclude bellows 308. The bellows 308 expands to provide protection ofthe heat exchanger system in the extended position. Additionally, thebellows 308 is configured to collapse or fold to enable the protectionsystem 302 to compress into the housing 304 when the heat exchangersystem is in the retracted position.

To illustrate the protection system 302 compressed into the housing 304,FIG. 12 illustrates the packaged unit 300 with the protection system 302in the compressed configuration. The compressed configuration may occurwhen the heat exchanger system is in the retracted position, such asduring operation of a heating mode of the packaged unit 300. In thisconfiguration, the bellows 308 is collapsed such that the protectionsystem 302 is compressed into the housing 306 of the packaged unit 300.To enable the flexibility to fold and strength to protect the heatexchanger system, the bellows may be made of PVC, fiberglass, nylon,rubber, canvas, another suitable material, or any combination thereof.Indeed, the bellows 308 may be formed from any durable yet flexiblematerial capable of withstanding environmental elements while shieldingthe heat exchanger system. When the protection system 302 is compressed,a side or external surface 310 may remain exposed external to thehousing 306 and continue to shield the heat exchanger system fromexternal elements. Thus, the external surface 310 may also provideprotection of the heat exchanger during the heating mode of the packagedunit 300. To provide adequate strength in protection, the externalsurface 310 may be made of metal, polymer, plastic, another suitablematerial, or any combination thereof.

Another embodiment of a protection system is illustrated in FIG. 13,which is a perspective view of a packaged unit 350. As shown in FIG. 13,a protection system 352 may include panel-like elements that areattached to a housing 354 of the packaged unit 350. The protectionsystem 352 also include an opening 356. During cooling mode, when a heatexchanger is in the extended position, the heat exchanger may movethrough the opening 356 of the protection system 352 while theprotection system 352 remains stationary.

For example, FIG. 14 illustrates the packaged unit 350 when the heatexchanger system 150 is moved into the opening 356 of protection system352. The heat exchanger system 150 may extend a distance such that anexternal surface 360 of the heat exchanger system 150 is flush orsubstantially flush with an edge 362 of the protection system 352. Inthis manner, only the external surface 360 of the heat exchanger isexternally exposed. The external surface 360 and the protection system352 may shield the heat exchanger system 150. To block the heatexchanger system 358 from extending too far out of the opening 356, theprotection system 352 may include stops, which are not shown in FIG. 14.For example, the stops may be disposed within the opening 356 and mayabut against a part of the heat exchanger system 150 at a certaindistance. The stops would provide a force to block the heat exchangersystem 358 from further extending out of the packaged unit 350. Thepackaged unit 350 may also use a controller, such as the controller 156,that is programmed to move the heat exchanger system 150 and stop itsposition at a certain distance. When the heat exchanger system 150 hasbeen moved to this position, the edge 362 may be substantially incontact with the perimeter of the external surface 360 to create a sealto prevent elements, such as precipitation, from entering the opening356. To provide adequate protection of the heat exchanger system 150,the protection system 352 may be made of metal, plastic, polymer,another suitable material, or any combination thereof. Furthermore, theexternal surface 360 may be made of the same or a different materialthan that of the protection system 352.

FIG. 15 is a perspective view of a packaged unit 400 illustrating anembodiment of a protection system 402 attached to a housing 404 of thepackaged unit 400. The protection system 402 includes a telescopicassembly 406 to enable the protection system 402 to extend and compress.For example, the telescopic assembly 406 includes a plurality ofsections, segments, or parts that slide out from one another to extendthe protection system 402 then the heat exchanger system 150 translatesout of the packaged unit 400. When the heat exchanger system 150retracts, the segments or section telescopically slide into one anotherto compress the protection system 402. In the extended position, thetelescopic assembly 406 protects the heat exchanger system 150 enclosedwithin the protection system 402. The sliding segments of the telescopicassembly 406 may also provide a seal around the heat exchanger system150 to block external elements, such as debris and/or precipitation,from entering the protection system 402. To enable the heat exchangersystem 150 to move into and out of the housing 404, the protectionsystem 402 may be attached to the packaged unit 400 at an opening 408 ofthe packaged unit 400.

FIG. 16 is a perspective view of the packaged unit 400 when theprotection system 402 is compressed and the heat exchanger system 150 iswithin the housing 404. As illustrated in FIG. 16, in the retractedposition, a small portion of the telescopic assembly 406 may remainexposed out of the housing 404. In addition, an external surface 410 ofthe heat exchanger system may remain exposed to protect the heatexchanger system 150 in the retracted position. As similarly discussedabove, the external surface 410 may be made of metal, plastic, polymer,another suitable material, or any combination thereof to protect theheat exchanger system 150 within the packaged unit 400.

Although FIGS. 11-16 discusses several embodiments of a protectionsystem, other embodiments of the protection system may be used to covera heat exchanger system when it is in an extended position. For example,some embodiments of the protection system may combine features of FIGS.11-16. It should be appreciated that, although the protection system isdepicted as rectangular in shape in FIGS. 11-16, other embodiments maybe a different shape to accommodate for the movement of the heatexchanger system, spatial or footprint considerations, or other designconstrains. Furthermore, movement of the protection system, such asexpansion and compression, may be controlled by a controller, such asthe controller 156.

As mentioned above, a controller may be configured to control operationof a packaged unit. FIG. 17 illustrates an embodiment of a method 450that the controller execute or perform to alternate or switch operatingmodes of the packaged unit. The packaged unit may begin at block 452 ina heating mode. As discussed, during the heating mode, a heat exchangersystem of the packaged unit may remain within the housing of thepackaged unit. The heat exchanger system may be coupled to a heat sourceand may operate to heat air flow within the packaged unit before the airflow exits the packaged unit. At block 454, the controller receives asignal to operate in the cooling mode. In some embodiments, the signalmay be generated because of a change in a desired temperature, such aswithin a building or room conditioned by the packaged unit. In responseto receiving the signal, at block 456, the controller translates theheat exchanger system out of the housing of the packaged unit. In someembodiments, the controller may also configure a protection systemattached to the packaged unit to adjust as the position of the heatexchanger system is adjusted. For example, the controller may expand theprotection system to enable the protection system to continue to enclosethe heat exchanger system during the cooling mode when the heatexchanger system is external to the packaged unit. Furthermore, thecontroller may adjust the interior of the packaged unit, such ascovering the heat source to block air flow from being directed to theheat source. After the heat exchanger is translated out of the packagedunit, the packaged unit may operate in the cooling mode, as shown atblock 458. As noted above, during operation of the cooling mode, the airflow may bypass the heat exchanger and flow directly out of the packagedunit.

The method 450 discusses switching from heating mode operation tocooling mode operation of the packaged unit. A similar method may beimplemented to switch from cooling mode operation to heating modeoperation. That is, the controller may receive a signal to operate inheating mode and, in response, may translate the heat exchanger systemfrom outside of the housing to within the housing of the packaged unit.Furthermore, additional steps may be added to the method 450. Forexample, the controller may adjust a blower of the packaged unit tooperate at a lower power such that the air flow exits the blower at alower velocity due to the lower resistance in the air flow path byvirtue of the heat exchanger system being positioned external to thepackaged unit in the cooling mode. Other adjustments of componentswithin the packaged unit may also occur when switching operation modes.

As set forth above, the heat exchanger system of the present disclosuremay provide one or more technical effects useful in the operation ofHVAC systems, such as packaged units, having a cooling mode and aheating mode. For example, in a heating mode, the heat exchanger systemmay be disposed within an air flow path of the HVAC system to enable aheat exchanger to heat an air flow. As the heat exchanger structureprovides hydraulic resistance that decreases a velocity of the air flow,the blower may compensate by increasing the velocity. In a cooling mode,the heat exchanger system may be translated and positioned out of theair flow path so the air flow may bypass the heat exchanger. As such,the blower may operate at a lower power to achieve a desired air flowvelocity. The HVAC system may also include a protection system thatencloses the heat exchanger system when the heat exchanger system isextended out of the air flow path. The protection system may thusprotect the heat exchanger system during the cooling mode. The technicaleffects and technical problems in the specification are examples and arenot limiting. It should be noted that the embodiments described in thespecification may have other technical effects and can solve othertechnical problems.

While only certain features and embodiments of the disclosure have beenillustrated and described, many modifications and changes may occur tothose skilled in the art, such as variations in sizes, dimensions,structures, shapes and proportions of the various elements, values ofparameters, mounting arrangements, use of materials, colors,orientations, and the like, without materially departing from the novelteachings and advantages of the subject matter recited in the claims.The order or sequence of any process or method steps may be varied orre-sequenced according to alternative embodiments. It is, therefore, tobe understood that the appended claims are intended to cover all suchmodifications and changes as fall within the true spirit of thedisclosure. Furthermore, in an effort to provide a concise descriptionof the exemplary embodiments, all features of an actual implementationmay not have been described, such as those unrelated to the presentlycontemplated best mode of carrying out the disclosed embodiments, orthose unrelated to enabling the claimed embodiments. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerous implementationspecific decisions may be made. Such a development effort might becomplex and time consuming, but would nevertheless be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure, without undueexperimentation.

1. A heating, ventilating, and air conditioning (HVAC) system,comprising: a heat exchanger configured to translate between a firstposition within an air flow path of the HVAC system and a secondposition external to the air flow path of the HVAC system.
 2. The HVACsystem of claim 1, wherein the heat exchanger is configured to translatevia springs.
 3. The HVAC system of claim 1, wherein the heat exchangeris configured to translate via a pulley system.
 4. The HVAC system ofclaim 1, wherein the heat exchanger is configured to translate via anactuator, a position control synchronous motor, a direct current motor,or any combination thereof.
 5. The HVAC system of claim 1, wherein theheat exchanger is configured to translate via a mechanical linkagesystem.
 6. The HVAC system of claim 1, comprising a protection systemconfigured to enclose the heat exchanger when the heat exchanger is inthe second position.
 7. The HVAC system of claim 6, wherein the heatexchanger is disposed within a housing, and the protection systemcomprises a bellows coupled to the housing on an external surface of thehousing.
 8. The HVAC system of claim 6, wherein the heat exchanger isdisposed within a housing, and the protection system comprises a panelcoupled to the housing on an external surface of the housing.
 9. TheHVAC system of claim 6, wherein the heat exchanger is disposed within ahousing, and the protection system comprises a telescoping assemblycoupled to the housing, wherein the telescoping assembly is configuredto extend from the housing when the heat exchanger is in the secondposition.
 10. The HVAC system of claim 1, comprising a blower, whereinthe blower is configured to operate at a lower power when the heatexchanger is in the second position.
 11. The HVAC system of claim 1,comprising a burner disposed within a housing of the HVAC system,wherein the burner is disposed within a first volume of the housing, theheat exchanger is disposed within a second volume of the housing, andthe first and second volumes are separated by a partition.
 12. The HVACsystem of claim 11, wherein the burner and the heat exchanger arefluidly coupled through the partition when the heat exchanger is in thefirst position.
 13. The HVAC system of claim 12, wherein the heatexchanger and the burner are decoupled from one another when the heatexchanger is in the second position.
 14. The HVAC system of claim 13,comprising a plate coupled to the heat exchanger, wherein the plate isconfigured to translate to a blocking position between the first volumeand the second volume adjacent to the burner when the heat exchanger istranslated to the second position.
 15. The HVAC system of claim 1,comprising a rooftop unit comprising the heat exchanger.
 16. A method ofoperating a heating, ventilating, and air conditioning (HVAC) system,comprising: operating the HVAC system in a first mode with a heatexchanger disposed within an air flow path; and operating the HVACsystem in a second mode with the heat exchanger positioned external tothe air flow path.
 17. The method of claim 16, wherein the first mode isa heating mode and the second mode is a cooling mode.
 18. The method ofclaim 16, comprising operating a blower at a first speed when the heatexchanger is within the air flow path and operating the blower at asecond speed when the heat exchanger is external to the air flow path,wherein the second speed is less than the first speed.
 19. The method ofclaim 16, wherein the heat exchanger is linearly translated from withinthe air flow path in the first mode to external to the air flow path inthe second mode.
 20. The method of claim 16, wherein the heat exchangeris attached to a burner in the first mode and decoupled from the burnerin the second mode.
 21. The method of claim 20, comprising translatingthe heat exchanger from within the air flow path to external to the airflow path, and translating a plate from a first position to a secondposition, wherein the plate is adjacent to the burner in the secondposition.
 22. The method of claim 16, comprising positioning the heatexchanger within a protection system configured to shroud the heatexchanger in the second mode.
 23. A packaged heating, ventilating, andair conditioning (HVAC) unit, comprising: a heat source disposed withina first volume of a housing of the packaged HVAC unit; and a heatexchanger disposed within a second volume of the housing of the packagedHVAC unit, wherein the heat exchanger is configured to establish a heatexchange relationship with an air flow within the housing in a heatingmode of the packaged HVAC unit, wherein the heat exchanger is configuredto translate from within the second volume to a position external to thesecond volume in a cooling mode of the packaged HVAC unit.
 24. Thepackaged HVAC unit of claim 23, wherein the heat exchanger is configuredto couple to the heat source in the heating mode.
 25. The packaged HVACunit of claim 24, wherein the heat exchanger and the heat source arecoupled to one another through a partition dividing the first volume andthe second volume in the heating mode.
 26. The packaged HVAC unit ofclaim 25, comprising a plate configured to translate along the partitionto a position adjacent to the heat source in the cooling mode.
 27. Thepackaged HVAC unit of claim 23, comprising a protection system coupledto the housing, wherein the protection system is configured to shroudthe heat exchanger in the cooling mode.
 28. The packaged HVAC unit ofclaim 27, wherein the protection system comprises a telescopic assembly,a plurality of panels, or a bellows.
 29. The packaged HVAC unit of claim23, comprising a blower disposed within the housing, wherein the bloweris configured to operate at a first speed in the heating mode and asecond speed in the cooling mode, wherein the first speed is greaterthan the second speed.
 30. The packaged HVAC unit of claim 29, whereinthe blower comprises a variable speed drive fan motor configured torotate a fan at the first speed in the heating mode and the second speedin the cooling mode.